Artificial limb and method of making the same



Aug. 29, 1950 T. J. SCHMIDT 2,520,659

ARTIFICIAL LIMB AND METHOD OF MAKING THE SAME Filed Feb. 11, 1946 za fla 2 w ATTOR N EY Patented Aug. 29, 1950 I ARTIFICIAL LIMB AND METHOD or MAKING: THE SAME Theodore John Schmidt, Portland, Oreg. Application February 11, 1946, Serial No. 646,832

The present invention relates to artificial limbs and provides a novel structure and m ethod of making the same. V

The principal objects of the invention are to provide an artificial body member, in the form of a leg, thigh, upper arm or forearm, which will be simple and inexpensive to make, light in weight, rigid and durable in use, and'well adapted to re- "ceive end connections for jointing to the member a cooperating element such as another limb member or an artificial hand, foot or the like of any more or less conventional construction.

An important object of the invention is to provide a method by which artificial limbs of any predetermined length and contour can be assembled from standard stock parts associated in any predetermined number and arrangement.

Further objects include the provision of an artificial limbwhich can be made from standard wood stock, such as plywood sheets, by workmen Other and further objects ofthe invention will i be made apparent to those skilled in the art by reference to the accompanying drawing" and following description thereof which disclose certain preferred embodiments of the invention.

In the accompanying drawing:

Figure 1 is a side elevational view of a stack of individual component elements of an artificial leg assembled in accordance with one of the preliminary steps of the method;

Fig. '2 is a similar view of the assembly after trimming to the desired contour of an artificial leg, and showing also a conventional form of artificial foot jointed to the assembly;

Fig. 3 is a, longitudinal median sectional view of the finished artificial leg;

Fig. 4 is an exploded view in perspective of three of the component elements of a limb made according to the principles of the invention; and

Fig. 5 is a side elevational view of an upper arm and forearm embodying the principles of the invention, jointed together and having an artificial hand of conventional form connected thereto.

The invention comprises essentially the assembly of a plurality of individual discs or annuli to provide a built-up stack having the shape of the desired leg or arm member. The individual elements are adhesively bonded together and are preshaped and selected relatively to each other to provide any desired external contour and overall length. The preferred material of which '5 Claims. (Cl. 32)

. 2 the individual disc or annulus elements are made is plywood, i. e., sheets of wood veneer adhesively bonded together with their grains crossing each Such plywood is a standard article of commerce which is well known and requires no further description or identification.

From such sheets of plywood a plurality of annuli I are cut in a number of difierent sizes having external'peripheries varying from that 01' the thinnest ankle or wrist which it may be desired to reproduce 'in an artificial leg or arm to the thickest calf or biceps that it may be desired to simulate. As shown in Fig. 4, each of these annuli I has an axial thickness equal to that of the plywood sheet from which it is cut and each has a radial width A sumcient to give the element appropriate strength, i. e., a width of as little as one-quarter or three-sights inch to as much as one inch. These dimensions are not critical and can be varied at will without departing from the principles of the invention.

The annuli are made in'graduated sizes, in respect to external diameter, in steps of about onequarter inch, and a large number of specimens of each of the different sizes are made.

" A smaller number of strengthening discs 2 are also'made in the same sizes as the annuli l The 7 discs 2 difier from the annuli I by being substantially solid but they may have central and marginal openings 3 drilled or otherwise formed through them to reduce their weight. Despite these weight-reducing openings the discs are substantially more rigid than the annuli because of the strengthening or reinforcing substantially radial ribs 4 defined by the openings.

With a sufiicient number of the discs and annuli fabricated and classified according to size, a selection of appropriate sizes is made in accordanc with some predetermined shape and length of limb to be manufactured. Assuming such limb is the leg shown in Figs. 2 and 3, annuli and discs will be selected and stacked in the manner indicated in Fig. 1. Each element of the stack is coated on its fiat, side surfaces with some appropriate Waterproof adhesive, such as an artificial resin cement, and the stack is then mounted in a glue press until the adhesive has set. The result is the rough approximation of an artificial leg shape as shown in Fig. 1.

It will be noted that the surface of the body shown in Fig. l is stepped and discontinuous, a condition which results from the graduated sizes and the cylindrical shape of the outer walls or the several annuli and discs. This outer surface is dressed in any convenient manner, as by ufactors;

turning the body in a lathe, followed by a sanding operation. This results in the formation of the smooth, continuous outer surface shown in Figs. 2 and 3. The result is an artificial leg which closely simulates the shape of a natural leg. The upper and lower ends of the body may be closed by solid discs, indicated at 5 in the figures, and these end discs may be drilled or otherwise treated to' provide-sockets, pivots or other types of connection-for an artificialfoot 6 at' thebottom'or straps and the like, not shown, at the top for connection to a stump.

The completed member mayg-havetitslsurface finished by any paint, varnish or thelikewhioih" is suitable for use on wood.

Fig. 5 indicates how an appropriateselection of discs and annuli elements .can be ,assembled to provide an upper arm I and'a forearm 8 and how the latter may have an artificial hand 935c cured to it and how it ,may be connected to th ir pperearm-:hmaspivotaioint- -I B.

The frequency eat which the a strengthening :discs:.2 -;are interposed; Iinthastaclc will \be deter cninedaby the-radial widthaof the annuli i, dthe I ilength :orfl thememher 420 ;be* made, thesdesired-as 1 ri idity and-st1zength :of tthe ,member, and. other =.-In a -leg tof approximately eighteen inches length about three such strengthening eiscs evlillg-gienerallyeberfoundrsuflicient, .asshowm Figs-3. -UnderiseinencircumstancesIewer' discsi serene: dises -iat' alla-may the used.

'FEhe c fmished member 7 extremely light and qiery durable. :Itds quiterrigid -yet itehas mum- .cienaiiexibility to yield-slightly withontibneakizog *under: the impact-10f "unusual :blows and strains. Because-the elements-rare vmadeczof plwiood, with their alternatively crossed i-grains, the assembly does :not' warp---.or.. split insthe away that-solid wooden artificial rbodyimembers {are apt. to do.

'iTheinyentien is capable of being-zembodiedinv otheruzamd idiflerentlyimodified terms, *all within Eii'lQt-ECOFE or .thetzappended claims;

:iaim: 7 1:1 gimethod-ofmakingran:artificial limb-comprising forming fromcsheets of v-plywoodrzeach "cpmprising grlurality of .layers: of wwood adhesively' c-bondeditogether with the grainsrof ad- ,iacentdayers crossing.eachrethercat-an angle -a plurality nfiannuli-hatdng flatside sunfaces': and

outer peripheries of different size, adhesively securing said surfaces of selected annuli to each other to provide a stack having the approximate over-all shape of a natural limb but differing externally therefrom by having an outer surface characterized by angular ofisets at the junctions of adjacent annuli, and then trimming the outer surface of the stack to remove said offsets and zeause'rthe pegiphzeries nfitheannnli 4:0; merge into each o'ther and therebyasimulate more nearly the shape of a natural limb.

'2. An artificial limb comprising a multiplicity loflannuliioiplywood, each annulus having a pluraJiW-nfthinlayers of wood adhesively bonded together with the grains of adjacent layers cross- ;ing-eachntherrat an angle and all of said annuli beings adhesively bonded coaxially together to form anelongatedstack having a generally holilowrinterior and having a relatively smooth convweight. I

JOHN SCHMIDT.

TREFERENCES ICITED The :iol-lowingesrefierences are-:of record in Kile-int this patent: 1

UNITED STATES-WATENTS 

